Integrated sonar system



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INTEGRATED SONAR SYSTEM Filed Oct. 29, 1952 4 Sheets-Sheet l A (I I FIG.IA.

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I DIFFER- AT 9 I ENCE TRANSDUCER I2 f INVENTORS I ROTOR OSCAR HUGOscIIucK ROBERT B. WATSON ATTORNEY Filed Oct. 29, 1952 O. H. SCHUCK ETALINTEGRATED SONAR SYSTEM 4 Sheets-Sheet 2 SWEEP CIRCUITS ,s\; r:&g20BRIGHTENING F we no SHIFTER 3 5"- f m Br s ,|9

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OSCAR HUGO SGHUCK ROBERT B. WATSON ATTORNEY y 1965 o. H. scHucK ETAL3,195,101

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PO -E 20mm m 5 m8 Em n8 cm United States Patent 3,195,101 INTEGRATEDSGNAR SYSTEM Gscar Hugo Schools, Minneapolis, Minn, and Robert B.Watson, Austin, Tex, assignors to the United States of America asrepresented by the Secretary of the Navy Filed 9st. 29, 1952, fier. No.317,382 filairns. (Qt. 340-3) This invention relates to underwater soundecho ranging systems and more particularly is directed to an integratedsonar system which is capable of furnishing information concerning theposition of a target in space.

Most sound echo ranging systems which have been used up to the presenttime have incorporated apparatus which gives target bearing and range inan essentially azimuthal plane only. With the advent of advanced firecontrol techniques and improved underwater ordnance, a system which willprovide further and more accurate detailed information as to thelocation of a target and its motion through the water is necessary. Totake full advantage of the improved fire control and ordnance, the soundsystem should measure, for example, azimuth bearing to i /z a degree atmaximum range, depth angle to i /z degree at 1,000 yards and targetrange to :10 yards at 1,000 yards.

It is the primary object of the present invention to provide a systemwhich will fulfill these specifications as closely as possible in thelight of present knowledge.

Another object of the invention is to provide a system in whichinformation'suitably corrected for the motions of the carrying ship isaudibly and visually presented to the operators.

Other objects and advantages of the invention will become apparent fromthe following description of a specific embodiment thereof taken inconnection with the attached drawings, in which:

FIGS. 1A and 1B, when joined together with the lines a through qmatching, form a single line block diagram of the electronic portion ofa system embodying the pres ent invention;

FIG. 2 is a block diagram of a receiver used in the invention;

FIG. 3 is a diagrammatic illustration of control features utilized inthe invention, and includes apparatus used to nullify their own Dopplereffect.

The preferred embodiment of the invention includes search and attackportions, in which only the search portion is utilized until the targetrange is closed to a predetermined extent as, for example, to 1,000yards, after which further detailed information is derived from theattack portion of the system. The search portion, however, remainscontinuously in operation.

Referring to the drawings, two separate transducers capable ofconverting electrical energy into accoustical energy and vice versa aredesignated 10 and 12 and are mounted one above the other on a commontraining shaft 14 so that they are adapted to be rotated in a 'planeparallel to the deck of the ship by a training motor 16 in response to asignal from a training motor control unit 18. The search transducer 10consists of a plurality of segments as disclosed in detail in copendingapplication Ser. No. 549,460 of Schuck, et al., filed August 14, 1944,now Patent No. 2,697,822, each of which is operated as a unit for theconversion of electrical energy into acoustical energy and vim versa.The transducer 16 is connected at suitable intervals to a searchtransmitter 20 through a junction box 22 containing suitablesend-receive relays.

For reception, the search transducer is connected through the junctionbox 22 to a system which is continuously alert in all directions andwhich has previously ice been described in said Schuck et al.,application Serial No. 549,460. This system comprises a scanning andbeam forming rotor 24 which receives the signal coming from thetransducer 10 and presents it to a brightening receiver 26 and the usualazimuth plan-position indicator (PPI) 28 on which the signal appears inform of a short brightened are or segment on a cathode ray tube.

The information which is available on the azimuth planposition indicator2% shows all targets within range of the apparatus simultaneously. It isdesirable, if a single target is to be examined, to provide a means tobreak down the information received on the search transducer so thatonly a particular segment of the transducer, covering for example of thehorizon, is utilized. For this purpose the transducer 10 is madetrainable in the azimuthal plane. Certain of the segments of the searchtransducer are connected to a search listening lag line 30, the outputof which is fed to a bearing deviation receiver 32. The lag line is soconstructed that, in effect, two closely spaced transducers are formedfrom the elements of the search transducer 10 and the output of the lagline comprises two channels which are compared in receiver apparatus 32in a suitable manner as for example as described in application SerialNo. 549,523, of Oscar H. Schuck, filed August 15, 1944, now Patent No.2,665,416. The output of the bearing deviation receiver 32 is utilizedto brighten and deflect the trace of a second cathode ray tube 34 and toactuate a loudspeaker 36. Similarly this output is also fed to ahorizontal range recorder 38 in the usual manner.

It will be recognized that the apparatus so far described is acombination of the scanning echo ranging system described in the abovecited Schucl: et a1. application Ser. No. 549,460, and a bearingdeviation indicator (BDI) with the modification that the bearingdeviation indicator takes its information from certain of the elementsof the common search transducer 10. Since this transducer is madetrainable, it is necessary to introduce a correction factor into thedisplay on the azimuth PPI indicator 28. The introduction of thiscorrection factor, which serves to maintain the relative bearing 000 atthe top of the screen regardless of the angle through which the searchtransducer is turned, will be described hereinafter under the controlfeatures of the invention.

The attack transducer 12 comprises, in the present instance, of an arrayof electrosonic elements which cover that portion of a cylindricalsurface which is necessary to transmit and receive a sound beam from anypoint in a vertical plane between a forward horizontal direction,downwardly past the center line of the ship and to a line pointing aboutrearwar-dly, taking into account the fact that the ship rolls and thusvaries the position of the transducer with respect to a horizontalplane. For this purpose it is only necessary to fill approximately 270of the surface of the cylinder with the electrosonic elements asindicated by the dotted line portions of 12 in FIG. 1A. In the preferredform, the attack transducer is divided into 48 staves ofmagnetostrictive laminations, each of which comprises a right and leftelement so that in effect two closely disposed partly cylindricaltransducers are provided. The attack transducer must be trainable sinceit scans in a plane perpendicular to the deck of the ship and the planemust be brought through the target if an echo is to be received.

The attack transducer is connected through an attack junction box 50 toan attack transmitter 52 and may be actuated either manually orautomatically, and at the usual varying pulsing rates. If desired thejunction box may include means to actuate only certain ones of thetransducer elements during transmission in order that a properlydirected beam may be emitted. This is advane3 tageous for in certainwaters it has been found that echoes from the bottom are so severe as toobscure a target echo by completely overloading the receiving system sothat a relatively sharp beam directed at an angle to the vertical isuseful in reducing the effect of bottom reverberation.

Once a sound pulse has been emitted from the attack transducer itstransducer elements are connected to the receiving position in thejunction box 50 and are scanned by an angle scanning rotor 54 which maybe either the capacitative or inductive type described in the abovementioned Schuck et al. application, Serial No. 549,460 or theelectronic type described in the copending application of Stanley R.Rich, Serial No. 563,042, filed November 11, 1944, now Patent No.2,703,396. In either event the information from the scanning rotor 54 isfed to a depth angle brightening receiver 56 and thence to an elevationposition indicator (EPI) and to a depth recorder 60. The system which isthus provided to scan in depth is, in effect, the counterpart of thesearch scanning system operating now in a vertical plane instead of ahorizontal plane. Sweep circuits 27, interposed in the circuit of thejunction boxes, scanning rotor and the individual indicators, areprovided to coordinate the integrated sonar system.

The sweep circuits 27 thus provide a beam sweep generating means for theindividual cathode ray indicator, direct and control the operation ofthe search and angle scanning rotors, and further, key the search andattack transmitters through the junction boxes. In so doing, the entiresystem is regulated to provide a single coordinated system.

As above stated the elements of the attack transducer 12 are subdividedto provide right and left halves so that information from these halvesmay be used to actuate the bearing deviation indicator EDT receiver 32.A switch 62 having Search and Attack positions is provided whichconnects the BDI receiver 32 to the listening lag line 30 in oneposition and in its other position connects this receiver to the depthscanning portion of the system. While it is possible to utilize a directconnection type of bearing deviation indicator it is more convenient toconnect the BDI receiver through rotatable scanning rotors orcommutators so that the bearing deviation indicator may be connected, atthe will of the operator, to any set of transducer staves so that thebeam of sensitivity may be rotated by him in the vertical plane. Forthis purpose the system includes a commutator-type sum listening rotor64 and a commutator-type difference listening rotor 66. These rotors 64and as are each similar in construction to the commutator and lag linecombination shown in FiGS. 4 and 5 of said copending application 549,460which effectively divide the attack transducer into two units. Thegeneral principle of this type bearing deviation indicator circuit is totake the voltages from two halves of the attack transducer 12, add theirvalues in the sum listening rotor 64 and amplify the resultant voltagein one channel; subtract their values in the difference listening rotor66 and amplify the resultant voltage in another channel; shift the phaseof each of these resultant voltages by a predetermined amount, forexample, 45, and finally to combine the outputs of the two channels in aphase sensitive rectifier to give a DC. voltage for operation of the BDIindicator 34 in a manner to be described more fully in connection withFIG. 2. The sum channel may also be conveniently used to provide avoltage for brightening the spot on the indicator 34 and power foroperating the range recorder 33 and speaker 36. Thus the receiver 32performs both the functions of a BDI receiver and a listening receiverat the same time.

For purposes of a relatively long range search the frequency ofoperation of the search transducer 18 and its associated elementsincluding the receiver 26 are best kept to a relatively low value, forexample 26 kc. However, for the close range attack system a higherfrequency with the better definition resulting therefrom is more usableso that the attack transducer and its transmitter and receiving partsare conveniently arranged to operate at a frequency of, for example, 38kc. Since the receiver 32 must operate with either transducer itscomponents must be selected and arranged to provide for thisinterchangeability.

As above noted, the bearing deviation receiver 32 is incorporated as thepreferred form of listening channel receiver. There are several knowndevices of this class which have been used, each of which produces anoutput reading which is dependent on the phase of arrival of sound wavesat two or more closely disposed hydrophones or at two or more parts of asingle hydrophone. Whenever the phase at the two hydrophones is the samethe deviation indication is zero. Since there are several possibledirections in which the phase of arrival can be the same, of which oneis normal to the face plane of two hydrophones, pure phase measurementalone is not relied on. Instead, a combination of phase and amplitude ismeasured by making the hydrophoncs directionally sensitive to a degreesuch that secondary zero indications are so small as to be negligible.

In the search channel, certain of the elements of the search transducer10, enough to give two satisfactory overlapping beamed responses,produce signals that are ultimately fed to the receiver 32 of the sumand difference type modified in an important respect by the addition ofa superheterodyne oscillator as indicated in the receiver block diagramFIG. 2. The usual sum and difference bearing deviation indicator is fedby the output of the two hydrophone halves, A and B, to the ends of atransformer primary 200 shown in FIG. 2. In one modification (parallelsplit), the hydrophone halves are connected so that for a signalarriving in phase the currents flowing in primary winding 200 fromrespective hydrophone halves A and B are 180 out of phase, and novoltage is induced in an associated secondary 201 which thus representsthe difference channel. The sum channel which is energized from atransformer primary 202 connected between the halves of primary 200 andground will contain a maximum signal for a wave train arriving in phaseat the two transducer halves due to the addition of the currentsoriginating from hydrophone halves A and B.

In general, the output from the transformer secondary 201 is theelectrical difference between the voltages developed by the twoeffective transducer halves; while the output from the sum transformersecondary 203 is the electrical sum of the two voltages developed by thetwo halves. If it is assumed that the outputs from the two halves areidentical in amplitude, the phase difference between the sum anddifference voltages thus formed is The signals contained in the sum anddifference channels are thus 90 out of phase, and since an indication oftheir relative magnitudes is desired it becomes necessary to introduce aphase shift in one or the other, or both channels sufficient to bringthem into phase with each other. This may be done at any point in thetwo channels prior to comparison, but in the present instance we preferto lower the signal frequency by mixing the signal in each channel withthe output of a local oscillator 204 in mixers 205, 206. At the sametime or preferably immediately thereafter, the phase shift is introducedby shifting the difference channel -45 and the sum channel +45.Experimental evidence has shown that phase inequality between the twoamplifier channels is not serious within at least 20 of the optimum, andamplitude inequalities within :2 db between the two channels are notdisturbing. The system is thus easily manufactured and adjusted sincethe component specifications need not be unduly strict.

Since a single oscillator 204 serves both channels, unicontrol of thereceiver and the transmitters of the systems becomes possible. The IFand subsequent filters of the receiver may remain fixed, with variationsin the frequency of echo ranging operation dependent on oscillator 204.

Thus, with unicontrol the output of oscillator 294 is mixed with theoutput of the usual transmitting oscillators contained in units 26 and52 in mixers so that the frequency of transmission, F becomes:

F =F F where P is the frequency of the master oscillator 2M F is thefrequency of the transmitter oscillator It will be seen that the [F ofthe receiver 32 (assuming no Doppler shift) is:

both of which remain fixed even though the frequency of transmission bechanged.

The phase shifted signals from 205 to 2% are amplified in separateamplifiers 2tl'7 and 298 and compared in a phase sensitive rectifier2&9. The DC. output of rectifier 209 is used to deflect the beam of theBDI indicator 34.

A part of the output of the sum channel is heat against a secondoscillator 212 in a mixer 213 and operates speaker 36 and, moreimportantly, is used to brighten the spot of indicator 34.

It will be understood that the roll and pitch of the searching ship willintroduce errors into the system indications and will move theecho-ranging beam of"? the line of sight to the target unless means areprovided to compensate for the angular displacement of the transducers.To this end the invention includes a stable element 1% and a trunniontilt corrector 102, shown in block form in FIGS. 1 and 3, which areincorporated in a standard two-axis stabilization system. The stableelement is a conventional ordnance unit including a gyroscope rotatingabout a vertical axis, the gimbals of which are trainable. In the typewhich has been used in connection with the present invention, the frameof the gyroscope is fixed to the deck and the movements thereof inresponse to rolling and pitching of the ship are taken by a magneticfield arrangement which is balanced when the gyroscope frame is in thevertical position but which becomes unbalanced when a magnetic elementcarried by the gyroscope frame is moved out of position in response to amotion of the ship. The unbalanced signals are transmitted by a servosystem to move the gimbals so as to return the gyroscope frame to thevertical position. Two outputs from the stable element provide thenecessary amount of motion of the gimbals. The third output from thestable element is the amount of rotation of the gimbals about an axisperpendicular to the deck of the ship. The amount of rotation of thegimbals about the axis perpendicular to the deck of the ship correspondsto the training of the transducer about this same axis. These threeoutputs are fed after certain modifications to be described hereinafterto the trunnion tilt corrector wherein are established the necessaryangular orders to maintain the echo-ranging beam along the line of sightto a target independent of ships roll and pitch.

The outputs from the trunnion tilt corrector are termed train order anddepression order. The former is used to train the transducers about anaxis perpendicular to the deck of the ship through training motorcontrol 18, and the latter is used only for the attack system, to selectby means of commutators 64 and 66, shown in block form in FIG. 1, theproper elements on the attack transducer to form a receiving beam ofsensitivity at the angle of the depression order measured in a planeperpendicular to the deck from the deck to the line of sight. The beamof sensitivity from the attack transducer is thereby directed in aspecific direction in space at all times, independent of the roll andpitch of the ship. It will be understood that the beam of sensitivity ofthe search transducer is stabilized at the same time as the beam for theattack transducer only when the two transducers are trained on the sametarget.

Under these circumstances the search transducer beam of sensitivity isalso pointed at the same target at all times independent of roll andpitch of the ship, since the means of determining bearing for the targetby the search transducer utilizes a plane perpendicular to the deck ofthe ship.

Referring to FIG. 1B, a cursor 13 i is provided at the face of thesearch plan-position indicator 28 to indicate the relative bearingposition of the trainable transducer Corrections of the cursors positionis established by an azimuth handwheel 1% and by a change in the shipscourse. The handwheel 1% is mechanically connected to the rotor elementof a conventional differential synchro generator 198 into which theships course is fed on one winding (derived from a conventional synchrogenerator 1519 which is mechanically coupled to this shaft of the gyrocompass 112), and, when combined with the position of the handwheel 155,"a quantity representing relative bearing of the target (relative to theship) results in the other synchro Winding of the differential generator193. The output of the differential generator indicating relativebearing of the target is fed through a conven tional servo link 1111which varies the position of cursor 104. The azimuth or bearing positionof the transducers 1i and 12 also are varied in response to the movementof the azimuth handwheel 1G6 and change in ship heading as indicated bythe movement of the gyro compass 112. Thus, this quantity, designated Bis used to position the cursor 164, and is also transmitted to thestable element where it is modified by a deck tilt corrector whoseoutput trains the gimbals of the stable element.

In the known scanning systems in which a stationary transducer coveringall or a predetermined portion of the horizon is used each transducerelement is connected to a corresponding commutator element and thesystem is so aligned initially that when a group of elements centered atrelative bearing 000 is activated by a signal from that direction a spotoccurs on'the indicator which is at the top of the screen. In thepresent system where the transducers are trainable it therefore becomesnecessary to introduce a correction factor to retain the same type ofindication as was obtained in the known scanning systems described abovesince the group of elements which were previously pointed dead ahead maynow be trained to a different angle so that'another group represents theforward looking sensitivity. This correction can be established byeither correcting the position of the commutator physically or byshifting the phase of its output through an angle equal to the relativehearing angle. Since the latter expedient is more convenient, theelectrical quantity representing B is utilized, through a conventionalservo system, to position a phase shifting transformer 11! shown inblock form in FIG. 1, in the spiral sweep line between the searchscanning rotor 24 and the associated indicator 23. The indication isthus corrected so that a signal always appears at its proper relativeposition on the screen regardless of the angle through which thetransducer is trained.

The controls for the attack portion of the system are somewhat moreinvolved and include a synchro generator 12% (see FIGS. 1 and 3), oneelement of which is driven by a depth handwheel 122 (which also variesthe vertical angle of the attack transducer reception further by varyingthe angular position of the sum and difference listening commutators byway of a differential synchro 134 rotated by movement of the handwheel122) so that the output of the synchro 12% is a function of the positionof the handwheel. This output is fed to a CT synchro 12 5, amplified andused to drive a motor 126 which in turn drives a cursor 128 operatingover the face of the elevation position indicator 58 to indicate theposition of the response pattern of the depth transducers as determinedby the position of the sum and difierence commutators 54 and 64. Thereis, therefore, an essentially mechanical connection between thehandwheel 122 and the cursor 128, the synchro and servo systems beingintroduced only for the reason that the electrical output of the synchro12.0 is utilized elsewhere in the system. This electrical output isdesignated E and is the depression angle between the line of sight tothe target and the horizontal plane measured in a vertical plane. Theelectrical quantity E is taken through another synchroamplifier system127 into a drive motor 130 the shaft of which is connected to and turnsthe rotor of a differential generator synchro 132 through an angle equalto E One Winding of this latter synchro is energized with a quantityrepresenting level which is the necessary motion of one gimbal to keepthe gyro gimbal horizontal, or the angle between the horizontal planeand the deck plane measured in a vertical plane passing through the lineof sight, so that one synchro winding contains a quantity E' which isthe target depression angle corrected for the roll and pitch of thecarrying ship as determined by the stable element.

Since it is necessary to indicate the true depression angle of thetarget on the screen of the indicator 53 the spiral sweep of thisindicator is corrected to introduce a phase shift equal to the correctedtarget depression angle E (output of T.T.C.) minus the actual depressionangle E For this purpose the shaft of drive motor 130 may be continuedto rotate synchro 132 and introduce angle E into the rotor thereof. Onewinding of synchro 132 is energized with a quantity E' i from the T.T.C.102 so that the other winding receives the correction quantity E 'E Thisquantity is fed to rotate a phase shifting transformer 136 inserted inthe spiral sweep for the indi cator 58 through servo positioning meansassociated therewith.

Differential synchro 134, which is driven by the motor 130, has theangle E introduced thereby and receives in one winding thereof theoutput from the stable element 100. The output of synchro 134 is thenfed to the trunnion tilt corrector 102 wherein the signal is transferredto the rotors 64 and 66 to thereby vary the vertical angle of the attacktransducer by varying the angular position of the sum and differencelistening rotors 64- and 66.

To enhance the usefulness of the listening channels of both the searchand attack portions of the system, apparatus is provided to eliminatetherefrom the frequency shift caused by motion of the attacking shipthrough the water. As a result of this nullification of the own Dopplershift, any change in frequency in the received signal from thetransmission frequency may be ascribed to motion of the target, and thisfrequency shift may be utilized in various ways to enhance theindication of the receiving and recording equipment. Various Dopplersensitive circuits have been proposed and used in connection with theBDI gear as well as with the range recorder. It is, of course,advantageous to indicate and/or record only echoes from moving targetsor to enhance these indications over echoes received from stationarytargets.

It is possible to introduce a correction factor for own Dopplernullification in a beamed sound system such as that represented by thelistening channels of both the search and attack portions of the presentinvention either at the transmitter or at the receiver with equalpotential effectiveness, although in the scanning portion, introductionat the receiver is less complicated.

There are available at the present time two types of own Dopplernullifiers which have been used and tested extensively. First, thereverberation controlled type described in the copending application ofLeon G. S. Wood, Serial No. 547,919, new Patent No. 2, and

ondly the computed correction type disclosed in the copendingapplication of O. H. Schuck, Serial No. 509,300, now Patent No.2,438,580.

A voltage proportional to ships speed may be readily obtained by knownapparatus operated by the ships log. This voltage S is fed to the statorwinding of a synchro resolver 160, or wound rotor induction apparatus inwhich the voltage induced in the rotor is varied sinusoidally as theangular position of the rotor is changed. If this angular position ischanged by an amount equal to B the relative bearing to which thetransducer is trained by motor 16 a voltage equal to S cos B may betaken from the rotor. This voltage is used to correct the receiverassociated with the search portion of the system, and is further appliedto the stator of a second resolver 162. The rotor of resolver 162 isturned through an angle 13,, by motor 130, so that a voltage equal to Scos B cos E is taken therefrom and applied to a local oscillator in theattack receiver 56 or in the attack transmitter 52. The application maybe in any portion of the oscillator circuit in a manner well known inthe art, for example to a reactance tube or to a capacitor in theoscillator tank circuit.

A switch 62, is used by the operator to connect the system for searchand attack functions, the principal alteration being the interpositionof the BDI receiver in alternate portions.

The operation of the system has been described in connection with thedescription of the components but is briefly restated here. Pulses ofenergy are transmitted from the search and attack transducers atdifferent frequencies. The pattern of the search transducer ispreferably such that the sound waves therefrom are distributed equallyover the entire horizon, while the pattern of the attack transducercovers only a predetermined angle in a plane vertical with respect tothe deck of a ship. As previously stated, the beam of the attacktransducer may be made narrow even in this plane in order to reducetroublesome bottom echoes.

While the search transducer is made trainable by mounting it on the samerotating shaft as the attack transducer in the form shown, equally goodresults can be attained if the trainability is limited to the attacktransducer alone. Under these circumstances the introduction of thecorrection factor B into the sweep circuit of the search indicator isreplaced by the correction factor B -B The search transducer is shown astrainable simply for convenience.

Received wave energy is scanned in a plane parallel to the deck of thecarrying ship by the search transducer and its associated scanningreceiver and all echoes are indicated as bright spots on the PPIindicator 28. If the operator so desires he can investigate any oneechoing body in greater detail by using the BDI receiver 32, loudspeaker36 and range recorder 38. For this purpose the BDI receiver is, asstated above, connected to only certain transducer elements and thetransducer is made trainable so that these elements can be centered onthe target in the usual manner of operation of a searchligh transducer.When it has been determined that an attack should be made on the echoingbody under investigation and the range closed to about 1,000 yardsswitch 62 is thrown to the attack position. Thereafter information istaken from the attack transducer which operates at a higher frequency inorder to avoid interference between the search and attack systems andfor reasons of constructional convenience. The search system continuesin operation, however, and gives target information on azimuth indicator28.

The energy received by the attack transducer is scanned in a planeperpendicular to the deck of the carrying ship and the associatedscanning receiver presents information on the depth recorder and on theEPI indicator as bright spots indicating the echoing bodies. The BDIreceiver 32 now receives its signal from the attack transducer which issplit into right and left segments so that the BDI indication is in adirection at right angles to the direction of scanning. This dual use ofthe attack transducer is highly advantageous.

Inasmuch as the carrying ship does not remain steady in the Water,correction factors are introduced to compensate for the roll and pitch,as these motions affect the position of the attack transducer and wouldnormally cause loss of the target spot during part of the time, and/ ora moving indication on the screen of the associated cathode ray tube.These corrections take the form of corrections of the transducer shafttrain angle, of the position of the depth listening commutators, and inthe electrical signal from the depth scanning commutator. With theproper stabilization factors introduced, the indication remainsstationary, and the true position of the target in the water is given tothe operator.

While the present invention has been disclosed in connection with aspecific apparatus, it will be appreciated that various modificationsand changes therein may be made and that additions and supplements willsuggest themselves to those skilled in the art.

What is claimed is:

I. In a sonar system, the combination of a pair'of split projectorstaves for each transducer element, a sum and difference typetransformer connected to said pair of staves, a first mixer channelconnected to the diiference secondary of said transformer, a secondmixer channel connected to the sum secondary of the transformer, anoscillator feeding a fixed frequency signal in mixing relation into saidchannels to modify the signals from said secondaries, means shifting thephase of at least one of the mixed signals in said channels to phaseidentity therebetween, amplifying means for the resulting phaseequalized signals, signal amplitude comparing means connected to saidamplifying means, and means responsive to said amplitude comparing meansfor indicating the relative amplitude, whereby the difference in signalsfrom said pair of taves provides a bearing deviation indication.

2. A system in accordance with claim 1 including means for selectivescanning by the transducer in a given plane, said means comprising saidpair of staves aligned in an effective plane normal to the scanningplane of said transducer.

3. The system of claim 1 wherein the phase of the difference voltage isretarded substantially forty-five degrees and the sum voltage phase isadvanced substantially forty-five degrees.

4. In a sonar system the combination of means for scanning within aplane comprising a pair of transducer elements elfectively disposed in adirection perpendicular to said plane for each elemental direction ofscanning, a sum and diiference type transformer having a pair of primarywindings connected to be energized by voltages in each of said pair ofelements, a secondary winding for each said primary sum and differencewindings, an amplifier channel for said sum voltage, a similar amplifierchannel for said difference voltage, an oscillator common to both saidchannels producing a fixed frequency, mixer means in each of saidchannels for mixing the output of said oscillator with said sum anddifference voltage, phase shift-ing means equalizing the voltage phasesin said channels, means responsive to the sum voltage amplified signalsfor indicating the presence of a signal representing reflect-ion from asonar object, and means responsive to the output of said amplifierchannels for indicating the relative magnitude of the sum and ditferencevoltages to indicate the degree of deviation of the direction of saidobject from the nearest elemental direction of scanning.

5. An attack sonar system comprising a directional depth transducer fordepth scanning, means for continuously moving the response pattern ofsaid second transducer to continuously scan in a plane at right anglesto the surface of the water, means for utilizing said directionaltransducer to detect sounds only in the vicinity of specific depthangles while said transducer is also continuously scanning, and meansoperatively connected with said latter means for indicating the bearingdeviation of the sound signals received at said specific depth angles.

6. The combination of claim 5 characterized further by respective meansfor varying the direction of the response patterns of said transducerwithout physical movement of said transducer including means fordividing said transducer into two spaced directive elements, a directionindicator device for measuring the direction of the signals received bysaid transducer when the directive response pattern thereof is in afixed position comprising means for summing up the signals received byone set of spaced directive elements coupled thereto, means forsubtracting the signals received by said latter spaced directiveelements, means rendering the sum and difference signals in phase witheach other, means comparing the amplitude of said in phase signalswhereby a measure of the direction of the signals detected by thetransducer is obtained.

'7. An attack sonar system for installation on a moving vehiclecomprising a first trainable directive azimuth transducer, a secondtrainable directive depth transducer, first commutator means connectedto said depth transducer to effectively divide said depth transducerinto two projector units and for selectively manually varying the depthangle of the response pattern of said depth transducer, compassstabilization means for maintaining the response pattern of saidtransducers in a fixed position relative to a target independent of thevehicle. motion by varying the bearing position of said transducersrelative to the center line of the said vehicle in response to a changein ship heading, means for moving said first commutator means inresponse to roll and pitch of said vehicle to vary the depth angle ofthe response pattern of said depth transducer relative to the centerline of said ship to maintain the said response pattern on targetirrespective of the position of said vehicle, means associated with saidfirst commutator means for determining the depth angle of the echoesdetected by the response pattern controlled by said first commutatormeans, second and third commutator means similar to said firstcommutator means associated respectively with said first and secondtransducers for forming respective response patterns which continuouslyscan the azimuthal and vertical depth planes, respective cathode raytube plan position indicator means including respective beam sweepgenerating means therefor for indicating the range and position oftargets respectively in the azimuthal and vertical depth planes,respective means responsive to change in ship eading and to the rollingof the ship for varying the phase of the azimuth and depth indicatorbeam sweep respectively to cause said indicators to accurately indicatethe relative bearing and true depth angles of respective targets shownthereon.

8. The combination of claim 7 characterized further by said azimuth anddepth indicators each including an index marker on the face thereof forindicating the azimuth position and the depth angle positionrespectively of the transducer and the response pattern controlled bysaid first commutator means, means for moving the index marker on theface of the azimuth indicator in response to a change in ship heading,said index marker on the face of said depth indicator movable only inresponse to a change in the manually positioned depth angle of theresponse pattern of said depth transducer.

9. An attack sonar system for installation on a moving vehiclecomprising a directional depth sound transducer for depth scanning,means for continuously moving the response pattern of said transducer tocontinuously cause same to scan in a vertical plane, means for utilizingsaid transducer to also detect sounds only in the vicinity of specificdepth angles while said transducer is also continuously scanning, meansassociated with said latter means for indicating the bearing of thesound signals received at said specific depth angles, a cathode ray tubeelevation position indicator for indicating the range and depth anglerelative to a horizontal line of the targets detected by said depthsound transducer, beam sweep generating means for said indicator, aphase control means for varying the phase of the output of the beamsweep generating means associated with said indicator, means forselectively varying the azimuth of the depth transducer, means formaintaining said depth transducer responsive to signals from a givendepth angle relative to a horizontal reference line independent of thephysical movement of the transducers, means associated with said phasecontrol means for varying the phase of the depth indicator sweep inresponse to the movement of the center line of said vehicle from ahorizontal plane.

10. An attack sonar system comprising a transducer trainable in a firstplane for receiving sound energy from a target, said trainabletransducer including a plurality of transducer elements arcuatelydisposed with respect to each other and said first plane, each of saidtransducer elements being divided into two sections symmetricallydisposed about a second plane perpendicular to said first plane, ascanning commutator connected to said transducer elements to produce adirectional characteristic shiftable in said second plane, a brighteningreceiver connected to said scanning commutator, a first cathode rayindicator having a brightening grid connected to said t2 brighteningreceiver and a deflectable electron beam, sweep means connected to saidscanning commutator and to said first cathode ray tube indicator toshift the direction characteristic of said transducer and the directionof deflection of said electron beam in synchronism with each other,second commutator means connected to said trainable transducer toprovide a selectable directional characteristic, an adjustable cursor onsaid cathode ray tube, means connected to said second commutator meansfor providing a first output proportional to the sum of the response ofthe connected transducer halves and a second output proportional to thedifierence between the response of the connected transducer halves,phase and amplitude comparison means connected to said first and secondoutputs to produce a deviation voltage varying in polarity and magnitudewith the direction and deviation of the target from said second plane, asecond cathode ray indicator including means for deflecting the electronbeam thereof, and means connecting said phase and amplitude comparisonmeans to said means for deflecting the electron beam of said secondcathode ray indicator, whereby to locate the target in two intersectingperpendicular planes.

No references cited.

CHESTER L. JUSTUS, Primary Examiner.

NORMAN H. EVANS, JACK H. LINSCOTT,

' Examiners.

1. IN A SONAR SYSTEM, THE COMBINATION OF A PAIR OF SPLIT PROJECTORSTAVES FOR EACH TRANSDUCER ELEMENT, A SUM AND DIFFERENCE TYPETRANSFORMER CONNECTED TO SAID PAIR OF STAVES, A FIRST MIXER CHANNELCONNECTED TO THE DIFFERENCE SECONDARY OF SAID TRANSFORMER, A SECONDMIXER CHANNEL CONNECTED TO THE SUM SECONDARY OF THE TRANSFORMER, ANOSCILLATOR FEEDING A FIXED FREQUENCY SIGNAL IN MIXING RELATION INTO SAIDCHANNELS TO MODIFY THE SIGNALS FROM SAID SECONDARIES, MEANS SHIFTING THEPHASE OF AT LEAST ONE OF THE MIXED SIGNALS IN SAID CHANNELS TO PHASEIDENTIFY THEREBETWEEN, AMPLIFYING MEANS FOR THE RESULTING PHASEEQUALIZED SIGNALS, SIGNAL AMPLITUDE COMPARING MEANS CONNECTED TO SAIDAMPLIFYING MEANS, AND MEANS RESPONSIVE TO SAID AMPLITUDE COMPARING MEANSFOR INDICATING THE RELATIVE AMPLITUDE, WHEREBY THE DIFFERENCE IN SIGNALSFROM SAID PAIR OF STAVES PROVIDES A BEARING DEVIATION INDICATION.